The Lost Ship of the Desert is one of my favorite urban legends. To quote Wikipedia:

The Lost Ship of the Desert is the subject of legends about various historical maritime vessels having supposedly become stranded and subsequently lost in the deserts of the American Southwest, most commonly in California’s Colorado Desert. Since the period following the American Civil War, stories about Spanish treasure galleons buried beneath the desert sands north of the Gulf of California have emerged as popular legends in American folklore… The Galleon, according to old timers, is now under the waters of the modern Salton Sea.